Method and system for predicting floating times of includsions during refininements of molten steel

Abstract

A method for predicting floating times of inclusions during refinements of molten steel includes: predicting a macroscopic multiphase flow field of the molten steel refining, injecting the inclusions into the multiphase flow field uniformly and randomly, determining a capture condition of the inclusions, calculating motion trajectories of the inclusions injected into the multiphase flow field, outputting captured inclusions' information through comparing the motion trajectory of the inclusion and the capture condition, and obtaining an average floating time, a relationship between a removal rate and the floating time, and the complete floating time through analyzing the captured inclusions' information. This method not only considers physical properties and sizes of the inclusions themselves but is also closely related to the refining process and the flow field in the refinement, and the results can provide theoretical basis for quantitative evaluation and optimization of the refining process and its parameters.

1 . A method for predicting floating times of inclusions during a refinement of molten steel, comprising following steps:
 S1, obtaining process parameters of the refinement of the molten steel, and predicting a macroscopic multiphase flow field during the refinement of the molten steel;   wherein the S1 specifically comprises:
 S1.1, determining a process for the refinement of the molten steel; 
 S1.2, obtaining the process parameters and operating parameters; 
 S1.3, determining physical parameters of phases of the molten steel, a refining slag, air and argon; 
 S1.4, establishing a multiphase flow model during the refinement of the molten steel, wherein the multiphase flow model comprises at least a molten steel phase and a refining slag phase; and 
   S1.5, solving the multiphase flow model to calculate and obtain the macroscopic multiphase flow field, wherein flow field data of the macroscopic multiphase flow field comprises at least a velocity, a turbulent energy, a dissipation rate of the turbulent energy, and volume fractions of the molten steel phase and the refining slag phase;   S2, injecting the inclusions into the molten steel uniformly and randomly according to the multiphase flow field obtained in the S1;   wherein the S2 specifically comprises:
 S2.1, obtaining regions of the molten steel phase in the macroscopic multiphase flow field during the refinement of the molten steel; 
 S2.2, determining a density and a diameter of the inclusions injected into the molten steel phase; 
 S2.3, determining a number N of the inclusions injected into the molten steel phase, wherein 10 4 <N<10 5 ; and 
   S2.4, injecting the inclusions into the molten steel phase in the macroscopic multiphase flow field randomly and uniformly, and taking this time as an initial time, t 0 =0;   S3, determining a capture condition of the inclusions injected into the multiphase flow field in the S2;   S4, calculating a motion trajectory of each inclusion injected into the multiphase flow field in the S2;   wherein the S4 specifically comprises:
 S4.1, taking random and uniform distribution of the inclusions in the molten steel phase in the S2.4 as an initial condition to calculate the motion trajectory of each inclusion in the multiphase flow field during the refinement of the molten steel; 
 S4.2, utilizing a discrete phase model to calculate the motion trajectory of each inclusion, and a motion equation of the inclusions being expressed by Newton's second law in the discrete phase model; solving an acceleration of each inclusion through forces acted on each inclusion, including a gravity, a buoyancy, a drag force, a virtual mass force, and a pressure gradient force; and describing influences of turbulences by a random walk model in the motion equation of the inclusions during the refinement of the molten steel; 
 S4.3, integrating the acceleration of each inclusion solved in the S4.2 over time to obtain a velocity of each inclusion; and 
   S4.4, integrating the velocity of each inclusion obtained in the S4.3 to obtain a position of each inclusion; and connecting position points of each inclusion at different times to obtain the motion trajectory of each inclusion;   S5, outputting information of captured inclusions and removing the captured inclusions, when the motion trajectories of the inclusions in the S4 meet the capture condition of the inclusions in the S3;   wherein the S5 specifically comprises:
 S5.1, obtaining a volume fraction of a slag phase in the position of each inclusion calculated in the S4.4; 
 S5.2, comparing the volume fraction of the slag phase in the position of each inclusion obtained in the S5.1 and a volume fraction of the slag phase determined in the S3; 
 S5.3, making the inclusion enter a next time step when the volume fraction of the slag phase in the position of the inclusion obtained in the S5.1 is no greater than 0.5; or determining the inclusion being captured by the refining slag when the volume fraction of the slag phase in the position of the inclusion obtained in the S5.1 is greater than 0.5, and taking this time as a floating time of the inclusion, denoted as t; 
 S5.4, recording and outputting relevant information of the inclusions captured by the refining slag, wherein the relevant information of the inclusions captured by the refining slag comprises initial positions of the inclusions, captured positions of the inclusions, and the floating times of the inclusions; and 
   S5.5, removing the inclusions captured by the refining slag from a computational domain; and   S6, analyzing the information of the captured inclusions obtained in the S5 to obtain an average floating time, a relationship between a removal rate and a floating time, and a complete floating time;   wherein the S6 specifically comprises:
 S6.1, performing arithmetic average on the floating times of all of the inclusions to obtain an average floating time t ave  through the following formula: 
   
       
         
           
             
               
                 
                   t 
                   ave 
                 
                 = 
                 
                   
                     1 
                     N 
                   
                   ⁢ 
                   
                     
                       ∑ 
                       
                            
                         
                           i 
                           = 
                           1 
                         
                       
                       
                            
                         N 
                       
                     
                     
                       t 
                       i 
                     
                   
                 
               
               ; 
             
           
         
         
           where N represents a number of the inclusions, t i  represents a floating time of an i-th inclusion; 
           S6.2, letting M=N×m % when the removal rate of the inclusions is m %; 
           6.3, sorting the floating times of all of the inclusions from smallest to largest to obtain a sequence Row; 
           S6.4, determining a floating time t m %  corresponding to the removal rate m % as a M-th value of the sequence Row, which is: 
           t m % =Row[M]; and 
           S6.5, determining the complete floating time t al  as a floating time corresponding to a removal rate of 99%, which is: 
           t al =t 99% . 
         
       
     
     
         2 . (canceled) 
     
     
         3 . The method as claimed in  claim 1 , wherein the process for the refinement of the molten steel in the S1.1 comprises: argon-stirred ladle, ladle furnace (LF) refining, ruhrstahl heraeus (RH) refining, or vacuum degassing (VD) refining. 
     
     
         4 . (canceled) 
     
     
         5 . The method as claimed in  claim 1 , wherein the step of determining a capture condition of the inclusions injected into the multiphase flow field in the S3 specifically comprises: when a volume fraction of a slag phase in a cell or a grid where one of the inclusions is located is greater than 0.5, the one of the inclusions is determined to be captured by a refining slag. 
     
     
         6 - 8 . (canceled) 
     
     
         9 . A system implementing the method for predicting the floating times of the inclusions during the refinement of the molten steel as claimed in  claim 1 , wherein the system comprises:
 a molten steel refining multiphase flow module, configured to obtain the process parameters of the refinement of the molten steel, and predict the macroscopic multiphase flow field during the refinement of the molten steel;   an inclusion floating motion analysis module, configured to calculate the motion trajectories of the inclusions and capture processes of the inclusions according to the macroscopic multiphase flow field during the refinement of the molten steel, and to output the information of the captured inclusions; and   a data analysis module, configured to calculate to obtain the average floating time, the relationship of the removal rate and the floating time, and the complete floating time according to the information of the captured inclusions.   
     
     
         10 . A non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium is stored with a computer program; and the computer program is configured to be executed by a processor to implement the method as claimed in  claim 1 .